Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2000-07-11
2002-06-25
Rausuer, Robert W. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C549S403000
Reexamination Certificate
active
06410699
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for preparation of isoflavone compounds from materials that contain isoflavone compounds, especially from those plants that are members of such families as Leguminosae, Rosaceae, Iridaceae, Morus, and
Amarantus inamoenus
. More particularly, the present invention relates to a-process for preparation of, isoflavone compounds, from leguminous plants, especially isoflavone aglycones that are hydrolysates of isoflavone glycosides.
2. Background Art
Isoflavone is represented by the following formula (I):
It has so far been known that isoflavone is naturally present in those plants belonging to Leguminosae, Rosaceae, Iridaceae, Morus and
Amarantus inamoenus
, especially in leguminous plants.
Isoflavone compounds or precursors thereof have the basic isoflavone structure represented by the above formula (I), and various substituents such as alkyl, hydroxyl or alkyloxyl groups.
Isoflavone compounds are represented by the following formula (II):
Representative examples of such isoflavone compounds are shown in Table A.
TABLE A
R
1
R
2
R
3
Designation
Glucose
H
H
Daidzin
Glucose
H
OH
Genistin
Glucose
Methoxy
H
Glycitin
H
H
H
Daidzein
H
H
OH
Genistein
H
Methoxy
H
Glycitein
Among the isoflavone compounds having the above formula (II), those ones whose R, is glucose are referred to as isoflavone glycosides, and hydrolysates of isoflavone glycosides are referred to as isoflavone aglycones.
In recent years, it has become known that isoflavone compounds have estrogen effect, antiestrogen effect, anti-oxidizing effect, antihemolytic effect, antibacterial effect, anti-lipemic effect, anti-cholesterol effect, anticonvulsant effect, cancered-cell-differentiation-inducing effect, oncogene-blocking effect, carcinostatic effect and other biological activities, and their utility is now attracting public attention.
There are many reports on the pharmacological effects of isoflavone compounds, especially isoflavone aglycones that are hydrolysates of isoflavone glycosides.
For instance, genistein, which is an aglycon formed when glucose contained in genistin, glycoside, is hydrolyzed, has been identified as a substance capable of inhibiting tyrosine kinase (TK inhibitor), tyrosine kinaseibeing essential for the induction of canceration by oncogene, and confirmed to have carcinostatic effect (Akiyama, et al.,
Biochemistry
, Vol. 59, No. 9, p. 1016 (1987)).
Further, among isoflavone compounds, genistein particularly shows estrogen effect, and has been confirmed to have therapeutic effect for osteoporosis and immunosuppressive effect.
Postmenopausal osteoporosis is now a great problem for women. The major cause of osteoporosis of this type is decrease in bone density accompanied by excessive metabolic turnover of bones induced by estrogen poyverty.
However, direct administration of estrogen, which is a typical means for treating osteoporosis, has the danger of side-effects to genital organs, causing, for instance, uterine or breast cancer. It is therefore beneficial also from the viewpoint of safety if isoflavone compounds can efficiently be extracted from edible leguminous plants, especially from soybeans, and utilized for health or prophylactic foods.
Since isoflavone compounds have pharmacological effects as mentioned above, there is now an increasing demand for the supply of isoflavone compounds in the medicine and food industries. However, isoflavone compounds are present in natural substances only in small quantities; in particular, isoflavone aglycones are contained in natural substances in extremely small quantities.
For instance, 95% or more of isoflavone compounds present in soybeans, which belong to Leguminosae, are isoflavone glycosides, and isoflavone aglycones are only 5% or less of the isoflavone compounds. For this reason, there is now a demand for a simple process for efficiently recovering isoflavone compounds, especially isoflavone aglycones, from materials containing isoflavone compounds in effective amounts.
To meet this demand, there has been reported, for example, a process for recovering isoflavone compounds from juice of soybeans steamed, using various synthetic absorptive resins (Zenzo KITADA, et al.,
The Journal of the Japan Society for Food Industry
, Vol. 33, No. 12, pp. 821-825, December 1986).
This report teaches such a method that juice of soybeans steamed is introduced as a starting material into a column filled with a resin, followed by elution with a water-containing alcohol to recover isoflavone compounds. However, the recovery percentages of the isoflavone compounds obtained are extremely low.
It is possible to obtain isoflavone compounds by the process described in Japanese Patent Laid-Open Publication No. 126186/1987. However, most of the isoflavone compounds obtainable by this method are daidzin and genistin, and isoflavone aglycones, which are isoflavone compounds desired, can be obtained only in low recovery percentages.
Further, there is a report entitled “Shoyu/miso no seizo-kotei ni okeru Isoflavone oyobi sono haitotai no bunpu-jotai kenkyu-ho (or Method for studying the Distribution of Isoflavone or Its Glycosides in the Process of Production of Soy Sauce/Miso) (1
st
report)”, Kiyoshi KIHARA,
Shoken
, Vol. 16, No. 5, pp. 190-194, 1990.
This report describes that, during fermentation of soybeans to produce soy sauce or miso, isoflavone glycosides are fully hydrolyzed to form isoflavone aglycones. However, this report teaches only a method for qualitatively or quantitatively analyzing isoflavone compounds to show the progress of the hydrolysis of isoflavone glycosides to isoflavone aglycones in each step of production of soy sauce or the like. This method is not suitable at all for the industrial production of isoflavone aglycones.
Japanese Patent Laid-Open Publication No. 170756/1993 describes a method for extracting isoflavone aglycones from isoflavone compounds contained in soy sauce cake or soy sauce oil. To obtain isoflavone aglycones in increased recovery percentages, the fact described in the above-described report that isoflavone glycosides are hydrolyzed to form isoflavone aglycones in the course of the production of soy sauce is applied to this method. However, the recovery percentages of isoflavone aglycones attainable by this method are not yet satisfactorily high.
Japanese Patent Laid-Open Publication No. 258669/1989 discloses a process for producing and recovering isoflavone aglycones, in which isoflavone glycosides are hydrolyzed with the aid of &bgr;-glucosidase, one of enzymes which soybeans themselves have. Practically, however, the yields of the isoflavone aglycones produced by this process are low.
The specifications of Japanese Patent Applications No. 32385/1994, No. 179111/1995, No. 26888/1995, No. 88552/1996, No. 83036/1997, etc. which the applicant of the present invention previously filed with the Japanese Patent Office disclose processes for producing concentrated isoflavone compounds containing isoflavone aglycones in large quantities. In these processes, isoflavone glycosides, which are present in legume in large quantities, are hydrolyzed by inoculating grains (soybeans, etc.) with microorganisms such as koji-kin, a fungus belonging to the genus
Aspergillus oryzae
. These are improved or modified processes established on the basis of the fact that isoflavone aglycones are efficiently obtainable from isoflavone glycosides.
Undoubtedly, the aforementioned prior techniques are improved methods useful for separating and recovering isoflavone compounds, especially isoflavone aglycones, from starting materials (methods for increasing the content of isoflavone aglycones by subjecting isoflavone glycosides to hydrolysis by various means being included). However, as far as we know, isoflavone aglycones cannot be obtained in satisfactorily high recovery percentages even by these conventional methods.
In most of the aforementioned prior techniques, especially in techniques represented by the method described in Japanese Patent Laid-Open Publ
Shiraishi Jitsuo
Takebe Minoru
Nichimo Kabushiki Kaisha
Rausuer Robert W.
Saeed Kamal A
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